This is correct. In fact SharpDevelop.TextEditor has been replaced by the WPF control SharpDevelop.AvalonEdit and is not available in the new version anymore. Since we are directly using SharpDevelop.TextEditor in HeuristicLab.CodeEditor and in turn in the ProgrammableOperatorView it would be necessary to rewrite the control to work with newer versions of SharpDevelop.

For the GPDL editor (#2026) I'm already using the newer SharpDevelop.AvalonEdit control because it is easier to adjust to custom languages.

Currently we're using a modified version of SharpDevelop.TextEditor where I removed all refences to log4net. I found it was not really an important part in those SD plugins that we use and easy to remove from their code.

After discussion with Erik I'm not sure that Mono-compatibility is a problem. After all SharpDevelop is a development environment for Mono also for Linux systems. Probably, the AvalonEdit component also works on Mono.

No, SharpDevelop only runs on the Windows platform (see [0]: Supported operating systems: Windows XP SP2 and later (eg Windows Server 2008 R2 and Windows 7)).
Actually the reason, why there is a own Mono IDE [1], is that it was not possible to port SharpDevelop (at least not the UI) to Mono/Linux.
There is some WPF support in Mono, but only the parts that were needed for running simple Silverlight applications. I don't know if this is enough to run the AvalonEdit, but I will try it out as soon as it is in the GPDL branch.

I'll leave this as it is now. I think there's no need to hide the cursor. While the script is running there is no indication that the code cannot be changed (grey background) and the cursor should be hidden.

Individual error markups are now only deleted if the marked section is edited. All error markups are deleted when the script is compiled and will be recreated as needed. the error markups of codeEditor.ShowCompileErrors can be shown again when double clicking on the error list